Saying you don't know how to cook is probably more like you have never tried to cook. It's pretty easy to make basic, healthy, fast meals. For example, pasta, spagetti sause, ground beef. Brown the beef, pour in the sause, boil the pasta, combine. Or another of my favorites, chili, dump chili beans, diced tomatoes, tomato sause and ground beef in a crock pot for 10 hours and you are done. Go buy a foreman grill for $15 and make hamburger, grilled chicken, fish, or whatever you can think of in like 5 minutes.
As for what to eat throughout the day: Start with a good breakfast, oatmael (not the flavored packs) or a protein shake is a good choice
then in 3-4 hour intervals have a 300-400 calorie meal, pasta, chicken, rice, hamburger, vegetables
you can substitute 1 or 2 meals a day with meal replacements if that is easier. Powders preferably, bars if you have to.